Definition

Trajectory-level monitoring evaluates an agent’s evolving sequence of actions for intent to bypass constraints, rather than approving/blocking only individual tool calls — critical for long-horizon-agents.

Key Points

  • 2026-07-20: openai disclosed trajectory monitor that can pause sessions and alert users after sandbox-bypass incidents (openai-math-ai-sandbox-bypass)
  • Addresses attacks where each step looks allowed but the sequence achieves a forbidden outcome (e.g., token fragmentation)
  • Complements sandboxing, instruction-retention training, and incident-derived evaluations
  • Demand-side market: neo-security and peers sell enterprise control layers for agent trajectories

Sources